Hanson Aggregates San Luis Obispo Storm Water Plan Review

Client: Hanson Aggregates, Mid-Pacific Region

Location: San Luis Obispo, California

Period of Performance: June - December 2004

ADH Task: ADH reviewed and revised Hanson's San Luis Obispo concrete facility's Augmented Stormwater BMP Plan. The active facility stores Portland cement ingredients including cement, fly ash and other admixtures, aggregate (sand and gravel and recycled concrete), and water. The Plan addresses the potential impacts to surface water associated with the concrete ingredients as indicated by TSS, specific conductance, and pH.

Augmented BMP Plan Summary:

• Batch Plant - Pump out or inspect at 72 hour intervals for vector control.
• Truck Washout Area - Pump out or inspect at 72 hour intervals for vector control.
• Drainage Retention Pond - Rebuild to 3000 cf capacity. Install drainage insert filter at discharge point. Pump out residual standing water after 72 hours.
• Inspections - Inspect above features and run-on from offsite during and after storm events.
• Street Sweeping of Paved Areas - In fall of each year and additionally as needed.
• Flow Control at Stockpiles - Flow control filtration devices should be in place prior to storm season, with truck access gaps that can be rapidly sealed.